From e9f8b10101c6da3ab000a2fb17162374c9bd2c69 Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Tue, 2 May 2017 18:16:53 +0200 Subject: [PATCH] tipc: refactor function tipc_sk_recvmsg() We try to make this function more readable by improving variable names and comments, plus some minor changes to the logics. Reviewed-by: Parthasarathy Bhuvaragan Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/socket.c | 121 +++++++++++++++++++++------------------------- 1 file changed, 56 insertions(+), 65 deletions(-) diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 8a4e9fe5f9eb..3855bfd1fb1b 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -51,6 +51,7 @@ #define TIPC_FWD_MSG 1 #define TIPC_MAX_PORT 0xffffffff #define TIPC_MIN_PORT 1 +#define TIPC_ACK_RATE 4 /* ACK at 1/4 of of rcv window size */ enum { TIPC_LISTEN = TCP_LISTEN, @@ -1290,7 +1291,7 @@ static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop) /** * tipc_recvmsg - receive packet-oriented message * @m: descriptor for message info - * @buf_len: total size of user buffer area + * @buflen: length of user buffer area * @flags: receive flags * * Used for SOCK_DGRAM, SOCK_RDM, and SOCK_SEQPACKET messages. @@ -1298,89 +1299,79 @@ static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop) * * Returns size of returned message data, errno otherwise */ -static int tipc_recvmsg(struct socket *sock, struct msghdr *m, size_t buf_len, - int flags) +static int tipc_recvmsg(struct socket *sock, struct msghdr *m, + size_t buflen, int flags) { struct sock *sk = sock->sk; struct tipc_sock *tsk = tipc_sk(sk); - struct sk_buff *buf; - struct tipc_msg *msg; - bool is_connectionless = tipc_sk_type_connectionless(sk); - long timeo; - unsigned int sz; - u32 err; - int res, hlen; + struct sk_buff *skb; + struct tipc_msg *hdr; + bool connected = !tipc_sk_type_connectionless(sk); + int rc, err, hlen, dlen, copy; + long timeout; /* Catch invalid receive requests */ - if (unlikely(!buf_len)) + if (unlikely(!buflen)) return -EINVAL; lock_sock(sk); - - if (!is_connectionless && unlikely(sk->sk_state == TIPC_OPEN)) { - res = -ENOTCONN; + if (unlikely(connected && sk->sk_state == TIPC_OPEN)) { + rc = -ENOTCONN; goto exit; } + timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); - timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); -restart: - - /* Look for a message in receive queue; wait if necessary */ - res = tipc_wait_for_rcvmsg(sock, &timeo); - if (res) - goto exit; - - /* Look at first message in receive queue */ - buf = skb_peek(&sk->sk_receive_queue); - msg = buf_msg(buf); - sz = msg_data_sz(msg); - hlen = msg_hdr_sz(msg); - err = msg_errcode(msg); - - /* Discard an empty non-errored message & try again */ - if ((!sz) && (!err)) { - tsk_advance_rx_queue(sk); - goto restart; - } - - /* Capture sender's address (optional) */ - set_orig_addr(m, msg); - - /* Capture ancillary data (optional) */ - res = tipc_sk_anc_data_recv(m, msg, tsk); - if (res) - goto exit; - - /* Capture message data (if valid) & compute return value (always) */ - if (!err) { - if (unlikely(buf_len < sz)) { - sz = buf_len; - m->msg_flags |= MSG_TRUNC; - } - res = skb_copy_datagram_msg(buf, hlen, m, sz); - if (res) + do { + /* Look at first msg in receive queue; wait if necessary */ + rc = tipc_wait_for_rcvmsg(sock, &timeout); + if (unlikely(rc)) goto exit; - res = sz; - } else { - if (is_connectionless || err == TIPC_CONN_SHUTDOWN || - m->msg_control) - res = 0; - else - res = -ECONNRESET; - } + skb = skb_peek(&sk->sk_receive_queue); + hdr = buf_msg(skb); + dlen = msg_data_sz(hdr); + hlen = msg_hdr_sz(hdr); + err = msg_errcode(hdr); + if (likely(dlen || err)) + break; + tsk_advance_rx_queue(sk); + } while (1); + /* Collect msg meta data, including error code and rejected data */ + set_orig_addr(m, hdr); + rc = tipc_sk_anc_data_recv(m, hdr, tsk); + if (unlikely(rc)) + goto exit; + + /* Capture data if non-error msg, otherwise just set return value */ + if (likely(!err)) { + copy = min_t(int, dlen, buflen); + if (unlikely(copy != dlen)) + m->msg_flags |= MSG_TRUNC; + rc = skb_copy_datagram_msg(skb, hlen, m, copy); + } else { + copy = 0; + rc = 0; + if (err != TIPC_CONN_SHUTDOWN && connected && !m->msg_control) + rc = -ECONNRESET; + } + if (unlikely(rc)) + goto exit; + + /* Caption of data or error code/rejected data was successful */ if (unlikely(flags & MSG_PEEK)) goto exit; - if (likely(!is_connectionless)) { - tsk->rcv_unacked += tsk_inc(tsk, hlen + sz); - if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4))) - tipc_sk_send_ack(tsk); - } tsk_advance_rx_queue(sk); + if (likely(!connected)) + goto exit; + + /* Send connection flow control ack when applicable */ + tsk->rcv_unacked += tsk_inc(tsk, hlen + dlen); + if (tsk->rcv_unacked >= tsk->rcv_win / TIPC_ACK_RATE) + tipc_sk_send_ack(tsk); exit: release_sock(sk); - return res; + return rc ? rc : copy; } /**